This invention relates generally to the manufacture of cushions such as used in seating and is particularly directed to apparatus for measuring and recording an impression of a person's seat contact contour, i.e., buttocks and thighs as well as dorsal and lateral trunk surfaces.
Recent advances in rehabilitation technology have improved the products available which cushion and support a person while seated. Maintaining a functional seated posture for a long period of time requires special support particularly for the elderly who incur more than 70% of reported pressure sores. Pressure sores arise from bony protuberances which cause areas of excessive pressure restricting blood flow to the surrounding tissue. In order to avoid pressure sores, the person must be frequently moved in those areas to which blood circulation has been restricted and massaged in attempting to prevent the formation of an ulcer. Appropriate body support is required to provide protection from this type of tissue trauma, prevent poor posture and enhance functional capabilities of those restricted to the seated posture.
Custom contoured cushions have been recognized as providing the support and comfort necessary for those who remain seated for extended periods. Various approaches have been undertaken to fabricate user contoured seat cushions which provide the desired support and comfort. One approach makes use of several aluminum templates which provide support and which are bendable to form a contoured support surface. This approach not only requires a separate cushion to be placed over the contoured support surface, but also provides a support surface which generally only remotely approaches the seating support surface contour of a user because of the difficulty in manually bending the aluminum plates to match the user's contour. Another approach employs a wooden frame having a plurality of apertures into which dowels are inserted in a snugly fitting manner. Each of the dowels may be chiseled down to a given length to match the support surface of an intended user. Upholstery including padding is then positioned over and in contact with the dowel ends to provide a continuous contoured seating surface. This approach is time consuming, expensive and generally unpredictable.
Yet another approach to forming a contoured seating cushion employs a flexible bag containing a granular material and fitted with a valve so that the bag can be maintained in a condition evacuated of air. The bag in its non-evacuated state is pushed against one who is to be supported and the granular material flows to allow the bag to take a shape closely conforming to the user's shape. The bag is then evacuated through the valve, causing the granular material to become pressed by virtue of the resulting pressure differential across the wall of the bag. The previously flexible support device thus becomes rigid, with the granular material becoming locked into a rigid support mass in a shape conforming to the shape of the body being supported. One problem with this approach is in the requirement for maintaining the bag in an evacuated condition for extended periods of time. As the bag becomes evacuated, or the vacuum is otherwise lost, conformance of the bag to the shape of a user is also lost.
Another approach, such as disclosed in U.S. Pat. No. 4,615,856 to Silverman, also employs bead-filled bags to make an impression of the seat and back portions of an intended user by evacuating the bags attached to a molding frame. A positive mold of the individual's respective backside and buttocks impressions are made, which is then utilized with another apparatus to mold a custom fitted seat cushion. Although capable of accurately contouring the cushions to an intended user's contour, this approach requires a rather expensive air bag fitted molding frame operated by one with specialized training.
Yet another approach creates a computer model of the cushion contours from data obtained through a contour measurement process which employs contour gauges designed to detect tissue deflection and contact with regular foam cushions. Data reflecting the pressure at the body-cushion interface is then used by the computer to control a three-dimensional milling machine for cutting out the cushion from a foam plastic blank. This approach requires sophisticated and expensive equipment used by one with special training in its control and operation.
The present invention addresses the aforementioned limitations of the prior art by providing a mechanical shape sensor for measuring the three-dimensional contour of a person's thighs and buttocks as well as one's dorsal and lateral trunk surfaces and providing a two-dimensional representation of this contoured surface to facilitate fabrication of custom contoured seat cushions. The mechanical shape sensor is inexpensive, easily operated, can be used to form seat cushions for even the most deformed and misshapen persons, and provides a contoured seating surface which matches that of an intended user with high accuracy.